Billy is afraid of……Bruce……Wayne?
Billy is able to see peoples aura, aura always change yet stay the same based on a persons mood, actions, mentality, and who they are as a person. 
As Caption Marvel, Billy has met a lot of interesting people with interesting yet fitting auras. Batman’s aura is a dark and heavy storm  full of faces crying.
When Billy heads to Gotham for WHIZ Radio where he attends a Gala with Morris as his chaperoned, Billy doesn’t really like the gala since all the rich peoples auras show them fake snakes looking down on him and his rented suit, so Billy sneaks away, where he meets Bruce Wayne.
Bruce: hello little one are you lost? 
Billy:No I’m fin—
Billy see Bruce’s aura is dark and gloomy that keeps on spiking back-and-forth. which freaks out Billy because this isn’t the bumbling floozy that he heard all about and it scares billy; now thinking that Bruce is a real dangerous man.
Billy: I-I-I..sooorrryyy * shaking like a leaf in a hurricane *
Bruce: !? Oh no no calm down, you’re fine * trying to keep his composure while trying to not draw attention*
This cause Bruce’s aura to change more, scaring Billy, even more to the point of tears
Billy: *now actively crying*
Bruce: *panicked*
Now a bunch of attention is on them, And paparazzi right now taking pictures 
Billy ran away, Bruce was confused and felt bad for scaring the kid